Prepartion of carboxylic acids from allylic compounds



Patented Jan. 26, 1.954

.rr orrrce:

Philip H=':1owle,..Hammond, Indi', andPhilip Hill,

Lansing, ,Ill-.,.assignors to-standard il Company; Chicago, .,Ill.',. a. corporation of *Iridiana No' llrawingr. Application December 28, 1951, Serial No. 263,983

This invention relates to thes= preparation of saturated 'carboxylicacidsiand hastparticular .ref erence to their preparation from,tertiary-olefins andrderivedlallylic halidesr lnzpetroleum irefinery gasstreams, particularly those from thermal and catalytic crackingcoperae r tions, sizable quantities of; olefin-i0. compounds. are-t0 befound; Ofztheseamajorportion usually, comprises:ethyleneand' nropylenerwhich' can be separated andpolymerizedto formuseful products.-. Another substantial portion consists of tertiary olefins such as isobutylene and its homologs. Aprimary object ofthe present invention is the provision of a... process. for converting this. sub.- stantia-Lportion of; refinery gasstreamsto saturated. aliphatic carboxylic acids: or-their salts. Another object of the-inventionis the provision of'a process for producing saturated aliphatic carb'oxylic acids, particularly :within'the rangeof four to about sixteen: carbonatoms-per.-v mol'ecule; A furtherobjectz-of: the inventioniisathewprovision offa processfor converting halogenatediolefins'to' saturated aliphatic 'carhoxylicacids; The invention has .for :other. obj ects-rsuchiother" advantages. or results as will appear in the specification: and claims hereinafter :mad'ei Brieflyv stated, the-present invention comprises the caustic oxidation-20f fa primary: allylic-halide, preferably the chloride: or": "bromide; in 1 which at least the betaccarbonatom. (the olefi'nic carbon atom adj oiningthe'halogenbearingcarbon-atom) is tertiary, the said oxidation essentially 1 including I bringing "the halides' into contact with a'pre heated. alkali, preferably-either sodium or potas sium hydroxide; The allylichalides-are obtained by halogenating'terti'ary 'olefins: The alkali can be apreheatedto above -.its-:-melting point so as I to provide a-liquicl oxidizingzmediumg orspreferabl-y; the alkali can be dispersed in an inert oill Whenemploying the preferred procedure; thesuspena sion'is preheated toa temperatnre' hetweenabout 175."and 350 C1, and preferably between 200"="and* 300? C, The allyli'c'halide'isbroughtqnickly into contact with the alkali-at the-= elevated tempera-- ture.:

The most surprisingaspect of our process-is the iact'that a saturated carboxylic acid isprepared from an unsaturated halide; Theioll'owing on usual reaction apparentlyoccurs: tlie' preheated alkali efiects an oxidation of the halogen radical, 5c and at the same time a-reduction of the olefinicbond of the olefinic halide. It is additionally notable: that thehalideis directly convertible to the; saturated: acid without the necessity of -"any-" intermediate ihydrolyzing' step;

Yields ofpotentialicommercial importance .are;

obtained primarily. because of .the .employment'ijofj" heatedslovvly, to this reaction temperature,.,side reactions, thattake place at lowertemperatures.

andjinclude, for example, the" formation offdi; allylic ether; lower the yields offthe. desiredfjacidi convenient and effective method *offrapidheating' is topheat'," to thereaction temperature,,a, slurry of the alkali in a non re'acting ,liquid. mee dinm such'as'a neutraljoill.

Materialsrthattare :usefulin the preparationof the saturated icarboxyli'c acids. are primary all'ylic; halides 'in which one1olefinic carbon .atom is tertiary in which the halogen radicalfis in anallyhc; position? and.is also primary, andi in which the. alkyl 'jradicals' contain at most about. ten" carbon atomsper' molecule: One relatively simple process'tfor preparing; these allylic halides, from-the tertiary; olefins' ccmprehends bringing, for exe ample; chlorine or'b'romine and the olefins into contact for a very brief reaction periodof between about 0.005 to 0.1 second'iandtlpreferably less than 0.01 second at atemperaturebetweenrabout.65? to ?."CL' while maintaining an-excess ofQthe-ol'efin equivalent .to a .ratio. of Iaboutlone ,mol .of olefin.

tobetweenv about, /2, andrA} moLof-the halogen;

Yields ash'ighas ,eighty-fivepercentby weight of" the fed stock mean can he=obtained Aplentiful source of the ally1ic...lia1ide@is isobutylene which. canlo'e chlorinatedto .form .methallyl chloride.

Eolymerizationoi butylene .and. isobutylene in refinery gas;streamsi yield butyl'enev codimer. and. diisobutylene oilwhichjhe .former comprises. at least .'.thirty to. thirty-five percent. 2,3,4-trimethyl nentene-li and-Ithe. latter...seventy-.five-. to eighty percent ,Z AA-tiimethyl ,pentenerL-n Other prod? ucts ofcbutylne polymerization. are; halogenated in a noneprimaryipositionc These compounds dc graderbymolecularvscission cluringcausticoxida tion and; are. consequently, readily. separable by fractional idistilla'tionirom the productacid.

In .a .pref erredinethodof $.c-arrying out the procofrinvention the.primary allylic chloride or.

romicle is- .brought into .contactwith an alkali essentially free. of noneassociated water suspended.v in an inert mediunniOr. example, lfieavywhiteoil.v a,.h"ighiy refinedfwhite .mineral oil. of. technical or medicinal, grade having av Saybolt. Universalviscosityatl00 F; of between about and 350) at temperatures.b'etween. about-200 and. 300 C.

and Lpreferablr 225 to -300 C and .at pressures?-. from atmospheric to vah'outflfiilll' pounds .persquare .1

inch gauge. The operating pressure, not highly critical, is generally governed by the vapor pressure of the employed halide at opening temperature.

Agitation of the allylic halide in the caustic-oil suspension improves yields and product quality. Evolution of gas from the reactant efiects some agitation. This gas, largely hydrogen, is evolved during the reaction period in the amount of about one mol per mol of allylic halide.

The alkali-metal salt of a saturated carboxylic acid having the same number of carbon atoms as that of the starting allylic halide is formed. The

corresponding free acid can be liberated from the reaction mixture by treatment of the latter with strong mineral acids.

Example 1 In an example of our process wherein a preheated alkali is used without an inert oil, 195 grams (3.0 moles) of a commercial potassium hydroxide, that melts at about 160 C., are placed in a stainless steel autoclave equipped with a stirring device. The autoclave was sealed and purged with nitrogen. Nitrogen was pumped into the autoclave to a pressure of 300 pounds per square inch gauge and the contents were heated with agitation to 260 C. A mol (90.6 grams) of methylallyl chloride was pumped into the hot caustic at a rate (about 3 cc. per minute) at which rapid heating of the introduced chloride was accomplished. The mixture was stirred, while maintaining the reaction temperature, for 35 minutes after the chloride addition was completed. The reactor-autoclave was cooled and nitrogen and reaction gas were vented. The reaction mass was dissolved in water, thus providing a solution of product salt, potassium chloride, and unreacted caustic. A yield of 71.8 mol percent of potassium isobutyrate was obtained. No substantial amount of degradation product, either acetate or formate, was detected in the reaction product.

Example 2 In this example, commercial grade methallyl chloride was employed as the feed stock. This allylic chloride was refractionated, and the fraction that distilled over within the range of 71 to -;-,72: C. was used as feed to the reaction zone.

'A preheated suspension of caustic potash was prepared-by placing 142 grams or 2.20 mols of potassium hydroxide pellets and 50 cc. of heavy white oil in a stainlessfsteelastirring autoclave, which was then sealed. Nitrogefi wasintroduced to a pressure of 200 pounds per sdufi'e dnch gauge and the mixture was heated with a tion to 260 C. Thereafter a solution of 90.6 grams or 1 mol of methallyl chloride in 90 cc. of heavy white oil was pumped into the hot caustic mixture at an average 1.1 cc. per minute. A noticeable increase in pressure was observed. The mixture was stirred for one hour following addition of the halide, making a total reaction period of 5 hours. After cooling, the nitrogen and reaction gas, or hydrogen, were vented. 800 cc. of water were added to dissolve potassium isobutyrate, potassium chloride and excess potassium hydroxide. The aqueous solution was separated and freed from neutral oils. The aqueous solution was acidified with sulfuric acid; the organic acid was separated and distilled to give a 73.2 mol percent yield of isobutyric acid having a boiling point of 98 C. at 105 mm. mercury. Other inspections showed 4 the following: n 1.3931; d4 0.947; neut. equiv., 88.6. The acid was further characterized through its p-bromophenacyl ester (M. P. 77.5-78.2 C.) which gave no depression of a mixed melting point when mixed with an authentic sample.

Example 3 Powdered potassium hydroxide in the amount of 70.7 grams, or 1.10 mols, was suspended in 150 cc. of heavy white oil in an alkali-resistant reactor, and was heated with agitation to 275 C. Olefinic chloride, that was prepared by the chlorination of diisobutylene and contained approximately of the primary halide, betaneopentyl allyl chloride, was added dropwise over a period of about two hours and until 73.3 grams, or 0.50 mols, had been added. The reaction mixture was maintainedfor another two hours at 260 to 275 C. during which time allylic chloride which distilled from the reaction mixture was recycled. During the reaction 0.52 mols of gas were evolved.

The mixture was cooled and 200 cc. of water were added to dissolve the potassium octanoate and potassium chloride. The aqueous solution was separated and freed from neutral oils. The aqueous solution was acidified with sulfuric acid and distilled to give the following fractions:

Weight Fraction B. P., e o. 53 Neut. Equiv. 32? Charge (so-70 0.110 mm 2. 6 100. o 3. s

. 70-1o0 o. 1o mm.--. 0. 9 103. 0 1. 2

-104" o. 1o mm 39. 7 144. 2 144.2 54.2

Upon a basis of 80 percent of primary chlo- (fraction 3) of 69% of theoretical was obtained. The product, octanoic acid, had the following values: 11. 1.4221, sp. gr., 0.891; and Brz No. 0.22 gms. Bra/100 gms. sample, or only 0.2 weight percent of olefin.

Our process has the advantages of being direct, in accomplishing two alterations of the reactant molecule in one step, and in avoiding losses which unavoidably arise from multiple-steps. Heretofore, the conversion of allylic halide to the corresponding saturated carboxylic acid has involved a multiplicity of steps comprising hydrolysis to the allylic alcohol, rearrangement of the allylic alcohol to the saturated aldehyde and finally oxidation of the aldehyde to the acid. Although clearly not equivalent to our process in that an additional step is involved, hydrolyzed allylic halides can be oxidized, preferably by a preheated disprsioriIoL-caustic in an inert medium, to obtain the corresponding saturated acid.

Organic carboxylic a'cids-.;are generally 'useful as intermediates in organid'synthesis. These acids are useful in the preparation of-N. .I. im-

provers in lubricating oils, oil additives, plasticizers, solutizers, hydrocarbon thickening agents, cellulose modifiers, varnishes, perfumes, flavors, irying agents, emulsifying agents, resins, and letergent compositions.

Having described our invention, we claim:

1. The process of preparing a saturated carboxylic acid directly from a primary allylic halide in which the halogen radical is selected from the group consisting of chlorine and bromine, an olefinic tertiary carbon atom adjoins the halogen-bearing carbon atom and theallylic halide contains a number of carbon atoms per molecule in the range of 4 to 8, which process comprises heating an alkali metal hydroxide to a temperature in the range of about 200 to 350 C. to provide a hot liquid oxidizing medium, slowly adding said primary allylic halide to said hot liquid oxidizing medium while agitating said medium and maintaining it in said range whereby the primary allylic halide is quickly raised to said temperature with the avoidance of side reactions that would take place at lower temperatures, continuing the agitation of the primary allylic halide in the hot reaction medium until a substantial amount of gas is liberated therefrom evidencing substantial conversion, acidifying the resulting alkali metal saturated carboxylic acid salt and recovering a saturated carboxylic acid from said salt, said carboxylic acid having the same number of carbon atoms per molecule as said allylic halide.

2. The process of claim 1 wherein the hot reaction medium includes a diluent consisting essentially of a heavy refined mineral oil.

p Q 3. The process of claim 1 wherein the primary allylic halide is methallyl chloride and the conversion is efiected under superatmospheric pressure.

4. The process of claim 1 wherein the allylic halide is beta-neopentyl allyl chloride.

5. The process of claim 1 in which the conversion temperature is in the range of 225 to 300 C.

PHILIP H. TOWLE. PHILIP I-IU'JL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,926,068 Strosacker Sept. 12, 1933 1,934,648 Strosacker et a1 Nov. 7, 1933 2,211,855 Kokatnur Aug. 20, 1940 FOREIGN PATENTS Number Country Date 424,659 Great Britain Feb. 26, 1935 

1. THE PROCESS OF PREPARING A SATURATED CARBOXYLIC ACID DIRECTLY FROM A PRIMARY ALLYLIC HALIDE IN WHICH THE HALOGEN RADICAL IS SELECTED FROM THE GROUP CONSISTING OF CHLORINE AND BROMINE, AND OLEFINIC TERTIARY CARBON ATOM ADJOINS THE HALOGEN-BEARIING CARBON ATOM AND THE ALLYLIC HALIDE CONTAINS A NUMBER OF CARBON ATOMS PER MOLECULE IN THE RANGE OF 4 TO 8, WHICH PROCESS COMPRISES HEATING AN ALKALI METAL HYDROXIDE TO A TEMPERATURE IN THE RANGE OF ABOUT 200 TO 350* C. TO PROVIDE A HOT LIQUID OXIDIZING MEDIUM, SLOWLY ADDING SAID PRIMARY ALLYLIC HALIDE TO SAID HOT LIQUID OXIDIZING MEDIUM WHILE AGITATING SAID MEDIUM AND MAINTAINING IT IN SAID RANGE WHEREBY THE PRIMARY ALLYLIC HALIDE IS QUICKLY RAISED TO SAID TEMPERATURE WITH THE AVOIDANCE OF SAID REACTIONS THAT WOULD TAKE PLACE AT LOWER TEMPERATURES, CONTINUING THE AGITATION OF THE PRIMARY ALLYLIC HALIDE IN THE HOT REACTION MEDIUN UNTIL A SUBSTANTIAL AMOUNT OF GAS IS LIBERATED THEREFROM EVIDENCING SUBSTANTIAL CONVERSION, ACIDIFYING THE RESULTING ALKALI METAL SATURATED CARBOXYLIC ACID SALT AND RECOVERING A SATURATED CARBOXYLIC ACID FROM SAID SALT, SAID CARBOXYLIC ACID HAVING THE SAME NUMBER OF CARBON ATOMS PER MOLECULE AS SAID ALLYLIC HALIDE. 